Apparatus for pneumatically classifying particulate materials



June 10, 1969 E. K. THOMSON 3,448,856

APPARATUS FOR PNEUMATICALLY CLASSIFYING PARTICULATE MATERIALS Filed Oct. 11, 1966 I INVENTOR 22) K 72 0/1150 J. .ZaV/J YTQQPMEL L ATTORNEY United States Patent US. Cl. 209-138 4 Claims ABSTRACT OF THE DISCLOSURE A solids classification and separation apparatus having a vertical housing open at the lower end and closed at the upper end by solids feed mechanism having a plurality of inverted frusto-conical bafiles aflixed within said housing. The housing supports a vertically adjustable axial member extending through its length that supports several frusto-conical members mounted thereon, the uppermost being fixed and the others being slidably mounted for movement in response to a gas stream passing upperwardly between said baflies and frusto-conical members countercurrent to the solids flow through the housing. The gas flow removes the fines from the solids stream through the upper portion of the housing and a suction fan, with the solids product being recovered from the lower end of the housing.

This invention relates to the pneumatic segregation or classification of particulate materials such as granular or pelletized carbon black, although not limited thereto.

In the production of pelletized and/ or granular products, such as carbon black, the normally present degree of abrasion or attrition produces an undesirable amount of fines or broken pellets or granules, and are often detrimental to the quality of the finished product.

It is among the objects of the present invention to elfectively segregate or separate undesirable fines from the remainder of the particulate material being handled.

Another object is the attainment of the foregoing ends by the use of apparatus which is comparatively simple and inexpensive to manufacture, install, operate and maintain.

The foregoing and other objects will become more fully understood from the following description to be read in conjunction with the annexed drawing wherein like reference numerals designate like parts and wherein:

The sole figure comprises a schematic representation of apparatus which has been constructed in accordance with the teachings of the present invention.

Referring more particularly to the drawing, the numeral 2 generally designates the main body portion of the housing of the apparatus of the present invention, the same comprising a cylinder of substantial height and diameter, which is preferably formed of metal and which may, if desired, be open at the bottom.

The upper end of the main body portion 2 of the housing merges into a superposed frusto-conical section 4, which, in turn, merges into a superposed short cylindrical section 6.

Disposed atop the upper end of the aforementioned frusto-conical section 4 of the housing is a suitable material inlet feed mechanism 8 which will permit the downward passage of granular or other particulate material while at the same time restricting the flow of air therethrough; for example, a conventional air-lock, as illustrated.

Within the cylindrical main body portion 2 of the housing is a series of vertically spaced inverted frusto-conical bafiles 10. 12 and 14, the larger diametrical portions of ice which are secured by welding or any other suitable means to the inner surface of said housing.

The smaller ends of the inverted frusto-conical bafiles 10, 12 and 14 are open; and, the cross-sectional areas of these openings are essentially identical. The central opening in the inverted frusto-conical baflles are smaller than the lower ends of the adjacent frusto-cones.

Axially disposed linear bearings or guide members 16 and 18 are respectively positioned adjacent the bottom of the cylindrical main body portion 2 of the housing and the upper end of the superposed frusto-conical portion 4; the said guide members receiving the lower and upper ends, respectively of an axially extending vertically adjustable control member 20, the purpose of which will be later described.

Slidably disposed on and extending radially of, the axially extending vertically adjustable control member 20 is a frusto-cone 24 the major portion of which occupies the area defined by the interior of the lowermost inverted frusto-conical balfle 10. The upper and smaller end of the lower frusto-cone 24 embraces the axially extending vertically adjustable control member 20 at a horizontal level which is considerably above the horizontal level of the upper and larger end of the lowermost inverted frusto-conical bafile 10, and the upper (and smaller) end of the frusto-cone 24 extends upwardly well into the areas defined by the interior of the intermediate inverted frusto-conical balfie 12.

Slidably disposed on, and extending radially of, the axially extending vertically adjustable control member 20 is a frusto-cone 26 the major portion of which occupies the area defined by the interior of the intermediate inverted frusto-conical baffle 12. The upper and smaller end of the frusto-cone 26 embraces the axially extending vertically adjustable control member 20 at a horizontal level which is considerably above the horizontal level of the lower and smaller end of the upper inverted frustoconical baffle 14.

Secured to, and extending radially of, the axially extending vertically adjustable control member 20 is a frustocone 28 the major portion of which occupies the area defined by the interior of the upper inverted frusto-conical bafile 14. The upper and smaller end of the frustocone 28 embraces the axially extending vertically adjustable control member 20 at a horizontal level which is considerably above the horizontal level of the upper and larger portion of the uppermost inverted frusto-conical baffle 14; and the lower (and larger) end of the frustocone 28, although larger than the lower (and smaller) end of the uppermost inverted frusto-conical baflle 14, is adapted for movement into relatively close adjacency with respect thereto when the axially extending vertically adjustable control member 20 is in its lowest adjusted position that is 28 moved in relation to 14.

One end of a conduit 34 extends through the frustoconical section 4 of the housing of the apparatus and communicates with the interior of the uppermost frusto-cone 28 through the medium of a flexible tube 36. The other end of the conduit 34 is connected to the inlet opening of a suitably driven fluid pump 38 having a discharge outlet 40.

The means for vertically adjusting the axially extending control member 20 may take any convenient form such as the outwardly extending manually operable pivoted lever 30 and associated linkage 32 shown in the drawings.

According to the foregoing construction and arrangement, including the slidable mounting means 22 of the lowermost and intermediate frusto-cones 24 and 26 on the axially extending vertically adjustable control member 20, the said frusto-cones 24 and 26 are free to move in response to difierential air pressure with the extent of such movement, assuming constant air volume, being controlled by means of weights 44 or other means such as springs and the like.

As will be more readily understood as this description proceeds, the apparatus operates on the principle that the smaller particles of fines, flakes and broken bits of granules and pellets are more easily air-borne than the larger granules and pellets. With the material in free-fall, through a stream of air, segregation of the material will occur. The fines will become air-borne and pass off with the stream of air and the more regular granules and pellets of greater mass then the fines will continue in freefall and pass through the apparatus. All other conditions being equal, the degree or extent of segregation or separation will be directly proportional to the velocity of the stream of air.

Operation The fluid pump 38 creates a flow of air through the apertures or zones indicated in the drawing at A, B, C and D and expelled from the fluid pump exhaust outlet 40.

The material to be segregated or separated is then fed through the feed mechanism and by gravity falls over the uppermost frusto-cone 28 which serves to disperse the (particulate) material onto the uppermost inverted frusto-conical batfle 14. This further dispersed the material into a relatively evenly dispersed flow of material otf the lower and smaller end of the inverted frusto-conical baffle 14 through aperture D onto the upper vertically slidable frusto-cone 26.

Air and particulate material are now simultaneously passing through the aperture D in opposite directions; or the air is passing through the dispersed material as it falls through the aperture D causing the fines to become air-borne. The fines segregated at this point will remain airborne and pass with the stream of air through the bottom of the frusto-cone 28, and through the flexible tube 36, conduit 34, and fluid pump 38 to be expelled at the exhaust outlet 40.

- The larger or more dense granules and particles will continue to fall by gravity onto the upper vertically slidable frusto-cone 26 and thence through aperture C onto the inverted frusto-conical baflle 12 where a segregation of particulate material will take place by fluidization and withdrawal of fines just as described in connection with aperture D. After passing through aperture C the solids move along the inside of inverted frusto-conical bafile 12 to the frusto-cone 24, through an aperture comparable to D above like segregation of material will occur at aperture B, as that previously described in regard to aperture C, and the particulate material then falls onto the lowest inverted frusto-conical bathe and out of the discharge aperture A of the apparatus.

As previously stated the degree of segregation or separation will be directly proportional to the velocity of the stream of air. The higher the velocity the larger the particles that will become air-borne. In the apparatus illustrated in the drawing the major portion of segregation will occur at aperture D and it is essential that at this point there be established a constant air flow of correct velocity and volume to achieve the segregation of the undesired fines from the remainder of the particulate material moving through the apparatus.

It is to be understood that the particulate material being treated and the air, or other fluid vehicle, are moving through the aperture D in opposite directions; and that a volume and velocity of air that is sufiicient to reverse the direction of flow of the fines in the material will be suflicient to maintain them in motion in the opposite direction to the flow of the remainder of the particulate material; that is, with the fines moving from the interior of the frusto-cone 28 through the flexible tube 36 and conduit 34 since the cross sectional area of the aperture D is greater than the cross sectional area of the conduit 34. This is due to two physical laws:

(a) the bodies in motion tend to stay in motion and (b) that where equal volumes of fluids pass through apertures of varying cross sectional areas the velocity of the fluid will be greater through the aperture of lesser area.

With the frusto-cones 26 and 24 (Which are slidably mounted on the axially extending vertically adjustable control member 20) in their lowest positions, their lower and larger ends contact, or substantially contact, the adjacent surfaces of the inverted frusto-conical baffles 12 and 10 respectively, the cross sectional area of the apertures C and B are restricted.

With the fluid jump 38 expelling air from within the frusto-cone 28 relatively adjacent the upper end of the apparatus, a pressure differential will develop across the frusto-cones 28 and 24 with the ambient air pressure outside of and adjacent the lower end of the apparatus tending to raise said frusto-cones. This pressure differential will continue to increase until such time as the frusto-cones 26 and 24 are raised, thereby increasing the areas of apertures B and C to permit air to flow to equalize the pressure differential. The pressure dilferential required to raise the frusto-cones 26 and 24 is directly proportional to the weight of the cones, which as beforementioned may be adjusted by means of the removable weights 44.

With the fluid pump 38 operating at a constant speed and output, and the appropriate weighting of the frustocones 26 and 24, pressure diiferential between the inside and outside of the housing can be maintained at a constant level.

It is to be understood that with the fluid pump 38 operating and no (particulate) material passing through the apparatus, the frusto-cones 26 and 24 will be suspended in a balanced condition on the axially extending vertically adjustable control member 20-, leaving apertures C and B of suflicient area to maintain a constant pressure differential between the interior and exterior of the housing of the apparatus to maintain said suspension.

With particulate material flowing through apertures C or B, or either of them, the said material will occupy a portion of the area of the aperture. This will result in a restriction of air flow and an immediate change in pressure differential across the respective frusto-cone (26 or 24) which will result in immediate movement of the frustocone to re-establish the balanced condition aforesaid.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. Apparatus for pneumatically classifying particulate materials consisting essentially of:

a substantially vertically disposed cylindrical housing;

a frusto-conical extension atop said housing;

means communicating with said extension for introducing particulate material thereinto;

a vertically adjustable control member disposed in and extending axially of said housing and extension thereof;

at least two spaced superposed inverted open-ended frusto-conical baflle members disposed in at least the top and bottom of said housing, with the peripheries of the upper and larger portions thereof in contact with the inner surface of said housing, and the exterior of the bottom housing baflle member being exposed to the atmosphere with its aperture being the fluidizing gas inlet and material discharge outlet;

a first frusto-cone affixed to said control member, with its upper portion extending into the extension atop said housing and its lower portion having a greater diameter than the lower opening of the upper housing baflle member and extending in an adjustable spaced relation into the lower portion of said baflie mem ber;

5 6 a conduit extending through the extension atop said 3. The combination of claim 1 together with means housing and communicating with the interior of said enabling the varying of the weight of said second-named frusto-cone; frusto-cone. a fluid exhaust pump connected to said conduit; and 4. The combination of claim 1 wherein there are three a frusto-cone slidably mounted on said control mem- 5 spaced superposed inverted open-ended frusto-conical ber below said first frusto-cone and above each bailie bafile members and two slidably mounted frusto-cones member, other than the uppermost, with the lower for cooperative association with the two lower frustoend of said frusto-cone having a greater diameter conical baflle members.

than the lower opening of said adjacent bafile member and being in interruptable contact and com- 10 References Cited munication only with the interior and the lower UNITED STATES N S portion of said baifie member, whereby said slidably mounted frusto-cone moves responsively to fluidizing 2 5 n 209 '150 gas pressure induced by said pump upon the interior 1 4452760 2/1923 D 209 150 and bottom of said frusto-cone by slidable upward 15 1914862 6/1933 l 209-150 movement on said control member forming a signifif 491 2/1953 i gga 209:136 cant and controlled aperture solely between said 3:306:443 2/1967 vSerene frusto-cone and the baffle member therebelow. 2. The combination of claim 1 together with means FRANK W. LUTTER, Primary Examiner disposed exteriorly of said apparatus for enabling the 20 vertical adjustment of said vertically adjustable control US. Cl. X.R. member. 209-150, 154 

